Heat Transfer By Convection - Practice Questions & MCQ

Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids. Convection is of two types - 

1. Natural convection : The main cause of this is the difference of densities at two places and is a consequence of gravity because on account of gravity the hot light particles rise up (density become less) and cold heavy particles (density become high) try setting down. It mostly occurs on heating a liquid/fluid.

2. Forced convection : If a fluid is forced(by means of fan or draught or any external means) to move to take up heat from a hot body then the convection process is called forced convection. In this case Newton's law of cooling holds good. According to which rate of loss of heat from a hot body due to moving fluid is directly proportional to the surface area of body and excess temperature of body over its surroundings.